PHYSIOLOGICAL ACTION OF NITROBENZENE VAPOR ON ANIMALS 465 
This is indicated by the hobble or sprawhng gait in walking, the position 
of the legs in standing, and other characteristics mentioned heretofore 
(page 462). 
Adiadochokinesis.— Adiadochokinesis is, perhaps, the best interpretation 
of the type of convulsions observed. ‘This is a term originally used by 
Babinski to describe a peculiar type of incoordination in patients (Jelliffe, 
1913). Itisseen in the absence of paralysis, muscle palsies, and sensibility 
disturbances, and is characterized by a loss of ability to carry out rapidly 
alternating movements, such as flexion and extension of the forearm on 
the arm. In dogs, birds, rats, and other animals poisoned by nitro- 
benzene, it was observed that at times one set of muscles wouldebe con- 
tracted and another set relaxed, and at other times just the reverse 
happened. For example, if motor impulses passed to the extensors of 
the hind legs, the animal was unable to stop these impulses or to use 
the antagonistic muscles, and the leg remained for a time rigidly extended; 
again, if the impulses passed to the flexors, then the animal was unable 
to extend the leg. This condition, according to Babinski, indicates 
involvement of the cerebellar paths. 
Nystagmus.— According to Jelliffe (1913), Holmes states that 
“nystagmus is acommon and very valuable localizing sign of local cerebellar 
lesions. It is almost certainly a true cerebellar symptom.” Nystagmus 
does not always appear, but when present it is invariably a cerebellar 
type, distinguishable from vestibular nystagmus by the jerky movements 
of the eyeball. The shifting is in a lateral plane, and is equally rapid 
in either direction. 
Asthenia.— Asthenia is one of the first symptoms to appear and is 
almost invariably present. The animal is usuaily so weak that when it 
is placed on its feet, its legs literally double up beneath it, and its head 
‘sways about as if the neck were disjointed. This symptom, according to 
Jelliffe (1913), indicates “disorder of the tractus cerebellovestibularis 
spinalis, or rubro-spinalis.”’ 
Hypotonus.— Hypotonus, as revealed by palpation of the muscles and 
by special tests of the tendon reflexes, was observed in the more advanced 
cases, especially, of nitrobenzene poisoning. In some cases this symptom 
was accompanied by poor tendon reflex reactions, while in other cases 
the tendon reflexes were normal or even exaggerated. These conditions 
indicate cerebellar hypotonus. 
